Breathe DeeplyX Saibou wa Fukaku Iki wo Suru; X Cell Is to Breathe Deeply; X Saibou wa Fukaku Iki o Suru - Energy; The Unknown Mitochondria Breathes Deeply; X Biological Cell Breathes Intensely ～energy～; X Cell Takes a Deep Breath ～energy～; X Saibou wa Fukaku Iki wo Suru: Energy; X細胞は深く息をする～energy～; X細胞は深く息をする

A battle ensues over life and death, belief and science, ethics and progress. Two boys, Sei and Oishi, fall madly in love with Yuko. Her death wreaks havoc on their young lives, bitter memories cease to fade, and their tender hearts cling to the dream of a world where debilitating illness disappears in the face of science. But what would happen if they discovered that all they believed was a lie? Is there still a chance that their suffering may end? Will mercy and love prevail?